When tuning a disc, do you do a quick bend or a slower, kinda holding the bend, bend?

I know Dave D said to fix a DX disc after a tree hit, its better to do a quick and abrupt bend to get it back to its original shape. A slower bend will tend to unbend. A tree hit is quick and that's why it holds that bend.

A tip that really helps is to run the disc under REALLY hot water for a little bit. This makes it softer and a little easier to bend. Then when you have it about where you want it, quickly run it under cold water to cool it back down.

I did this to a few discs that took a good tree hit and bent a section of the nose down. I couldn't bring it back until I ran it under hot water.

You might be shocked how many time a premium disc will need to be tunned to finally hold a tune. You do not want to tune right before you throw, unless of course you want the disc to be drastically tuned. You will need to tune a premium plastic disc several times with rest in between to get it just right. The disc will return to shape after a tune during the resting period.

"The reasonable man adapts himself to his environment. The unreasonable man adapts his environment to himself, therefore all progress is made by unreasonable men."-George Bernard Shaw

First, you must understand that there are two types of deformation, elastic and plastic.

Elastic deformation is the stage that any material goes through where, when deformed, it will return to its original shape every single time. Once there is enough deformation to go past this stage, the material is said to have enter plastic deformation.

Plastic deformation is actually where the material is being deformed and will not return to shape.
Take for example a rubber band. If you expand a rubber band a little it will always return to shape, and you can literally do this indefinitely (and it will not matter what speed you do it at). Now if you take the same rubber band and expand it out wide it will permanently stretch out of shape.

The same thing applies to plastic used in discs. For discs, the better the plastic the greater the elastic range and the greater the limit of plastic deformation. In other words, it takes a much greater deflection to permanently deform better plastics. Cheaper plastics permanently deform at much less defection. This explains why premium plastic discs do not “beat in” from collisions like cheaper plastics (this also explains why some plastics simply SUCK for discs because they permanently deform within the force collision range of normal tree hits).

So, to answer your question, the speed of the deflection is not the key, it is the AMOUNT of the defection (think of the rubber band example). Star discs and ESP discs take bending the rim nearly double back on itself to deform the disc.